As government mandated fuel economy and emissions regulations continue to tighten, more pressure is being applied to vehicle manufacturers to find new technologies that will increase fuel economy and minimize emissions from internal combustion engines. At the forefront of the new emissions and fuel economy technology is the electrification of the vehicle powertrain. Electrification enables sophisticated control options for powertrain components that are traditionally directly coupled to engine speed. Additionally, some hybrid systems have been proposed which introduce new fuel conservation techniques, such as start-stop technology.
Vehicles typically include a cooling system to dissipate heat developed by the vehicle power plant, such as an internal combustion engine. In a typical vehicle, the cooling system moves coolant through the engine. The coolant flowing through the engine absorbs heat and transfers it away from the engine. However, heat from the coolant must ultimately be dissipated to the air by passing air through the radiator. If the vehicle is moving with significant velocity, the ram air forced through the radiator is often sufficient to cool the radiator. However, when the vehicle is moving at low velocity, a fan is required to move air through the radiator.
These cooling fans are driven in a number of different ways. A wide range of systems are available to transmit power from the engines to the rotating cooling fans. Some of these include on/off clutches and viscous fan drives. With these devices or systems, a continuous belt is utilized to transfer rotating energy from the vehicle engine to the cooling fan of the fan drive systems.
There is a need for improved fan drive systems that assist in the vehicle and engine thermal management. There is also a need for thermal systems which can improve fuel economy and reduce undesirable vehicle emissions.